vivid: remove some unused vars

vivid: remove some unused vars

Gcc 6.1 warns about some unused vars. Remove them:
drivers/media/platform/vivid/vivid-vid-cap.c:40:2: warning: 'tpf_default' defined but not used [-Wunused-const-variable=]
  tpf_default = {.numerator = 1,  .denominator = 30};
  ^~~~~~~~~~~
drivers/media/platform/vivid/vivid-sdr-cap.c:54:27: warning: 'NUM_FORMATS' defined but not used [-Wunused-const-variable=]
 static const unsigned int NUM_FORMATS = ARRAY_SIZE(formats);
                           ^~~~~~~~~~~

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>